Various methods exist for retrieving valuable components of “spent” lithium-ion secondary batteries in order to re-use the components in a recycled battery product. Specifically, the lithium-transition-metal oxides comprising the cathode active materials (e.g., LiCoO2, LiMn2O4, LiNiO2, LiNiCoO2, Li(LiNiCoMn)O2, and LiNiCoMnO2) are of particular value in any lithium-ion battery recycling process. In order to retain their value in a recycled product, these materials must be recaptured at a high degree of purity, and free from contaminating metals such as aluminum, copper and iron, which if not removed would adversely affect the cycling performance and energy density of the recycled product. Iron is easily removed by exploiting its magnetic properties. The most effective way to isolate the valuable metal oxides from aluminum and copper is by dissolution of one or all of the desired or undesired components.
U.S. Pat. No. 6,514,311 uses hydrochloric acid to dissolve the transition-metal oxide into solution, followed by electrolysis to plate the pure metal out of solution. The metal must then be processed back into the lithium metal oxide in order to be usable again in a lithium-ion cell, U.S. Pat. No. 6,524,737 uses a dilute hydrochloric acid solution at elevated temperature to dissolve aluminum and copper while trying to minimize the deleterious effects on LiCoO2, highlighting the practical trade-off between the efficacy of unwanted-material dissolution versus valuable-material preservation in an acidic environment. U.S. Pat. No. 6,844,103 provides a method for isolating LiCoO2 from what they term a “cathode paste” comprising solely cathode materials, but provides no details on how such a pure starting material can be separated from the initial lithium-ion product. In practice, the initial isolation of purely a cathode material would be both impractical and inefficient, or less that 100% effective.